Of all the energy resources on earth one of the most abundant is coal. It is estimated, at todays rate of use, the world's coal supply could last 300 to 400 years. Not only is the supply of coal great but its heating value to cost ratio is favorable.
Despite the positive aspects of coal there is one seemingly overriding factor which prevents its wide spread use, i.e., coal pollutes the atmosphere upon burning. Of particular concern is its SO.sub.2 pollution which has been linked to the phenomenon of acid rain. The level of SO.sub.2 produced upon burning is apparently directly proportional to the sulfur content of the coal. It is a commonly accepted industry standard that coal which contains more than one percent sulfur is to be labeled a medium or high sulfur content coal depending upon the extent which the sulfur content exceeds one percent for the particular coal being graded. Low sulfur coal, of course, contains less than one percent sulfur. A typical low sulfur coal is Eastern Kentucky Cannel Coal. As would be expected, low sulfur coals are in great demand by the utility, metallurgical, and other coal consuming industries. This great demand places a premium price on low sulfur coal.
The mining, processing, storage and transport of coal, due to its relatively fragile nature, produces waste which is composed of coal pieces of small size, i.e., an apparent diameter of less than 3/4 inch. This waste coal, especially if it is a low sulfur coal, would have a high value if it could be reconstructed back to a usable size without deleteriously effecting its burning or emission characteristics. Such reconstruction entains the development of coal compositions which include, besides the coal, a binder to hold the small coal pieces together so that the reconstructed coal can withstand shipping and burning without premature crumbling. Several candidate compositions are disclosed in U.S. Pat. Nos. 4,331,446; 4,260,395; 4,169,711 and 4,417,899. U.S. Pat. No. 4,302,210 teaches the manufacture of a fuel log from sawdust, charcoal powder, and wax binder. While the candidate compositions may have utility if the coal component is a porous, soft coal, it is not certain they would be useful if the coal component is a hard, smooth, non-porous coal such as the before mentioned low sulfur Cannel Coal. Further, the candidate compositions, to be successful in a high tonnage commercial process, would have to have a high speed binding characteristic. Even though no testing of these candidate compositions has been performed, it is suspected they would not exhibit the high speed binding sought for the type of commercial production to which the subject invention is directed.
It is therefore an object of the invention to provide a coal composition for use in the high speed commercial reconstruction of waste coal. It is a further object of this invention to provide a coal composition having high utility even if the coal component is a hard, smooth, non-porous coal such as Cannel Coal.